Anti-tuberculous agents are a group of medications specifically used to treat tuberculosis (TB), a serious infectious disease caused by the bacterium Mycobacterium tuberculosis. TB most commonly affects the lungs but can also affect other parts of the body. Treating TB requires a combination of several drugs taken for a prolonged period to effectively kill the bacteria and prevent the development of drug resistance.

Understanding anti-tuberculous agents is essential for nurses involved in the care of patients with TB, including administering complex drug regimens, monitoring for side effects, and ensuring patient adherence to treatment.

Principles of TB Treatment

The treatment of TB is guided by several key principles:

• Combination Therapy: Multiple drugs are used simultaneously because M. tuberculosis can easily develop resistance to a single drug. Using a combination of drugs targets the bacteria through different mechanisms and significantly reduces the risk of resistance.

• Prolonged Treatment Duration: TB bacteria are slow-growing and can lie dormant in the body. Treatment typically lasts for 6 to 9 months, sometimes longer, to ensure all bacteria are eradicated.

• Directly Observed Therapy (DOT): For many patients, especially in public health programs, DOT is recommended or required. This involves a healthcare worker or trained observer watching the patient take their medications. DOT helps ensure adherence to the complex drug regimen, which is critical for treatment success and preventing drug resistance.

First-Line Anti-Tuberculous Agents

The standard treatment for drug-susceptible TB involves a combination of four first-line drugs in an intensive phase, followed by a continuation phase with fewer drugs. The most common first-line drugs are:

1. Isoniazid (INH): A cornerstone of TB treatment. It is bactericidal against actively growing bacteria and bacteriostatic against dormant bacteria.

2. Rifampicin (Rifampin): Another essential drug. It is bactericidal and works by inhibiting bacterial RNA synthesis. Rifampicin is also used to treat other infections.

3. Pyrazinamide (PZA): A bactericidal drug that is particularly effective in the acidic environment within macrophages, where TB bacteria can reside. It is used during the intensive phase.

4. Ethambutol (EMB): A bacteriostatic drug that prevents the bacteria from building their cell wall. It is used in the intensive phase, often to prevent the development of resistance to other drugs, especially if INH resistance is suspected.

Second-Line Anti-Tuberculous Agents

Second-line drugs are used to treat drug-resistant TB or when patients cannot tolerate first-line drugs. These drugs are often less potent, more toxic, and require longer treatment durations. Examples include:

• Fluoroquinolones (e.g., Levofloxacin, Moxifloxacin)

• Injectable agents (e.g., Streptomycin, Amikacin, Kanamycin – though injectables are being used less frequently with newer oral options)

• Other oral agents (e.g., Ethionamide, Cycloserine, Para-aminosalicylic acid – PAS)

• Newer drugs for drug-resistant TB (e.g., Bedaquiline, Delamanid, Pretomanid)

Important Considerations and Nursing Implications

Caring for patients on anti-tuberculous agents requires careful monitoring and patient support.

• Adherence is Crucial: The most significant challenge in TB treatment is ensuring patients take their medications consistently for the entire duration. Non-adherence can lead to treatment failure, relapse, and the development of drug-resistant TB, which is much harder to treat.

  • Nursing Role: Educate patients about the importance of completing the full course of treatment. Explain why combination therapy and long duration are necessary. Address barriers to adherence (cost, side effects, forgetfulness, social factors). Support DOT programs if applicable.

• Side Effects: All anti-tuberculous drugs can cause side effects. Nurses need to monitor for these and educate patients on what to report.

  • Isoniazid (INH): Peripheral neuropathy (tingling, numbness – often prevented with Vitamin B6/Pyridoxine supplementation), hepatotoxicity (liver damage – monitor liver function tests, educate on signs like jaundice, dark urine, fatigue), optic neuritis (vision problems – educate on reporting visual changes).

  • Rifampicin: Hepatotoxicity, gastrointestinal upset, rash, flu-like symptoms. Causes orange-red discoloration of urine, sweat, tears, and other body fluids. Educate patients that this is a harmless side effect but can stain contact lenses and clothing. Rifampicin also has significant drug interactions, accelerating the metabolism of many other medications (e.g., oral contraceptives, warfarin, certain HIV medications).

  • Pyrazinamide (PZA): Hepatotoxicity, joint pain (arthralgia), hyperuricemia (increased uric acid levels, can precipitate gout).

  • Ethambutol (EMB): Optic neuritis (can lead to irreversible blindness – educate on reporting visual changes, color vision testing may be done before and during treatment).

  • Second-Line Drugs: Often have more severe side effects, including hearing loss, kidney damage, psychiatric effects, and severe gastrointestinal issues. Close monitoring is essential.

• Monitoring:

  • Monitor liver function tests (ALT, AST, bilirubin) regularly, especially with INH, Rifampicin, and PZA.

  • Monitor kidney function tests (creatinine) for drugs excreted by the kidneys.

  • Monitor visual acuity and color vision with Ethambutol.

  • Monitor for signs and symptoms of peripheral neuropathy.

  • Monitor for signs of drug resistance (if symptoms do not improve or worsen).

• Infection Control: For patients with pulmonary TB, implement respiratory isolation (airborne precautions) until they are no longer considered infectious (usually after completing a period of effective treatment and having negative sputum smears). Educate patients on cough etiquette and respiratory hygiene.

• Nutrition: Encourage good nutrition to support the immune system and overall health.

• Patient Education: Provide comprehensive education about TB disease, the treatment plan, the importance of adherence, potential side effects and how to manage or report them, infection control measures, and the importance of follow-up appointments.

• Public Health Role: Nurses in public health settings play a key role in contact tracing, screening, and managing TB patients in the community, often utilizing DOT.